/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.sound.sampled;

/**
 * A <code>FloatControl</code> object provides control over a range of
 * floating-point values.  Float controls are often
 * represented in graphical user interfaces by continuously
 * adjustable objects such as sliders or rotary knobs.  Concrete subclasses
 * of <code>FloatControl</code> implement controls, such as gain and pan, that
 * affect a line's audio signal in some way that an application can manipulate.
 * The <code>{@link FloatControl.Type}</code>
 * inner class provides static instances of types that are used to
 * identify some common kinds of float control.
 * <p>
 * The <code>FloatControl</code> abstract class provides methods to set and get
 * the control's current floating-point value.  Other methods obtain the possible
 * range of values and the control's resolution (the smallest increment between
 * returned values).  Some float controls allow ramping to a
 * new value over a specified period of time.  <code>FloatControl</code> also
 * includes methods that return string labels for the minimum, maximum, and midpoint
 * positions of the control.
 *
 * @see Line#getControls
 * @see Line#isControlSupported
 *
 * @author David Rivas
 * @author Kara Kytle
 * @version %I%, %E%
 * @since 1.3
 */
public abstract class FloatControl extends Control {
    
    
    // INSTANCE VARIABLES
    
    
    // FINAL VARIABLES
    
    /**
     * The minimum supported value.
     */
    private float minimum;
    
    /**
     * The maximum supported value.
     */
    private float maximum;
    
    /**
     * The control's precision.
     */
    private float precision;
    
    /**
     * The smallest time increment in which a value change
     * can be effected during a value shift, in microseconds.
     */
    private int updatePeriod;
    
    
    /**
     * A label for the units in which the control values are expressed,
     * such as "dB" for decibels.
     */
    private final String units;
    
    /**
     * A label for the minimum value, such as "Left."
     */
    private final String minLabel;
    
    /**
     * A label for the maximum value, such as "Right."
     */
    private final String maxLabel;
    
    /**
     * A label for the mid-point value, such as "Center."
     */
    private final String midLabel;
    
    
    // STATE VARIABLES
    
    /**
     * The current value.
     */
    private float value;
    
    
    
    // CONSTRUCTORS
    
    
    /**
     * Constructs a new float control object with the given parameters
     *
     * @param type the kind of control represented by this float control object
     * @param minimum the smallest value permitted for the control
     * @param maximum the largest value permitted for the control
     * @param precision the resolution or granularity of the control.
     * This is the size of the increment between discrete valid values.
     * @param updatePeriod the smallest time interval, in microseconds, over which the control
     * can change from one discrete value to the next during a {@link #shift(float,float,int) shift}
     * @param initialValue the value that the control starts with when constructed
     * @param units the label for the units in which the control's values are expressed,
     * such as "dB" or "frames per second"
     * @param minLabel the label for the minimum value, such as "Left" or "Off"
     * @param midLabel the label for the midpoint value, such as "Center" or "Default"
     * @param maxLabel the label for the maximum value, such as "Right" or "Full"
     */
    protected FloatControl(Type type, float minimum, float maximum,
			   float precision, int updatePeriod, float initialValue,
			   String units, String minLabel, String midLabel, String maxLabel) {
	
	super(type);
	
	this.minimum = minimum;
	this.maximum = maximum;
	
	this.precision = precision;
	this.updatePeriod = updatePeriod;
	this.value = initialValue;
	
	this.units = units;
	this.minLabel = ( (minLabel == null) ? "" : minLabel);
	this.midLabel = ( (midLabel == null) ? "" : midLabel);
	this.maxLabel = ( (maxLabel == null) ? "" : maxLabel);
    }
    
    
    /**
     * Constructs a new float control object with the given parameters.
     * The labels for the minimum, maximum, and mid-point values are set
     * to zero-length strings.
     *
     * @param type the kind of control represented by this float control object
     * @param minimum the smallest value permitted for the control
     * @param maximum the largest value permitted for the control
     * @param precision the resolution or granularity of the control.
     * This is the size of the increment between discrete valid values.
     * @param updatePeriod the smallest time interval, in microseconds, over which the control
     * can change from one discrete value to the next during a {@link #shift(float,float,int) shift}
     * @param initialValue the value that the control starts with when constructed
     * @param units the label for the units in which the control's values are expressed,
     * such as "dB" or "frames per second"
     */
    protected FloatControl(Type type, float minimum, float maximum,
			   float precision, int updatePeriod, float initialValue, String units) {
	this(type, minimum, maximum, precision, updatePeriod, initialValue, units, "", "", "");
    }
    
    
    
    // METHODS
    
    
    /**
     * Sets the current value for the control.  The default implementation
     * simply sets the value as indicated.  If the value indicated is greater
     * than the maximum value, or smaller than the minimum value, an
     * IllegalArgumentException is thrown.
     * Some controls require that their line be open before they can be affected
     * by setting a value.
     * @param newValue desired new value
     * @throws IllegalArgumentException if the value indicated does not fall
     * within the allowable range
     */
    public void setValue(float newValue) {
	
	if (newValue > maximum) {
	    throw new IllegalArgumentException("Requested value " + newValue + " exceeds allowable maximum value " + maximum + ".");
	}
	
	if (newValue < minimum) {
	    throw new IllegalArgumentException("Requested value " + newValue + " smaller than allowable minimum value " + minimum + ".");
	}
	
	value = newValue;
    }
    
    
    /**
     * Obtains this control's current value.
     * @return the current value
     */
    public float getValue() {
	return value;
    }
    
    
    /**
     * Obtains the maximum value permitted.
     * @return the maximum allowable value
     */
    public float getMaximum() {
	return maximum;
    }
    
    
    /**
     * Obtains the minimum value permitted.
     * @return the minimum allowable value
     */
    public float getMinimum() {
	return minimum;
    }
    
    
    /**
     * Obtains the label for the units in which the control's values are expressed,
     * such as "dB" or "frames per second."
     * @return the units label, or a zero-length string if no label
     */
    public String getUnits() {
	return units;
    }
    
    
    /**
     * Obtains the label for the minimum value, such as "Left" or "Off."
     * @return the minimum value label, or a zero-length string if no label	 * has been set
     */
    public String getMinLabel() {
	return minLabel;
    }
    
    
    /**
     * Obtains the label for the mid-point value, such as "Center" or "Default."
     * @return the mid-point value label, or a zero-length string if no label	 * has been set
     */
    public String getMidLabel() {
	return midLabel;
    }
    
    
    /**
     * Obtains the label for the maximum value, such as "Right" or "Full."
     * @return the maximum value label, or a zero-length string if no label	 * has been set
     */
    public String getMaxLabel() {
	return maxLabel;
    }
    
    
    /**
     * Obtains the resolution or granularity of the control, in the units
     * that the control measures.
     * The precision is the size of the increment between discrete valid values
     * for this control, over the set of supported floating-point values.
     * @return the control's precision
     */
    public float getPrecision() {
	return precision;
    }
    
    
    /**
     * Obtains the smallest time interval, in microseconds, over which the control's value can
     * change during a shift.  The update period is the inverse of the frequency with which
     * the control updates its value during a shift.  If the implementation does not support value shifting over
     * time, it should set the control's value to the final value immediately
     * and return -1 from this method.
     *
     * @return update period in microseconds, or -1 if shifting over time is unsupported
     * @see #shift
     */
    public int getUpdatePeriod() {
	return updatePeriod;
    }
    
    
    /**
     * Changes the control value from the initial value to the final
     * value linearly over the specified time period, specified in microseconds.
     * This method returns without blocking; it does not wait for the shift
     * to complete.  An implementation should complete the operation within the time
     * specified.  The default implementation simply changes the value
     * to the final value immediately.
     *
     * @param from initial value at the beginning of the shift
     * @param to final value after the shift
     * @param microseconds maximum duration of the shift in microseconds
     *
     * @see #getUpdatePeriod
     */
    public void shift(float from, float to, int microseconds) {
	setValue(to);
    }
    
    
    // ABSTRACT METHOD IMPLEMENTATIONS: CONTROL
    
    
    /**
     * Provides a string representation of the control
     * @return a string description
     */
    public String toString() {
	return new String(getType() + " with current value: " + getValue() + " " + units +
			  " (range: " + minimum + " - " + maximum + ")");
    }
    
    
    // INNER CLASSES
    
    
    /**
     * An instance of the <code>FloatControl.Type</code> inner class identifies one kind of
     * float control.  Static instances are provided for the
     * common types.
     *
     * @author Kara Kytle
     * @version %I%, %E%
     * @since 1.3
     */
    public static class Type extends Control.Type {
	
	
	// TYPE DEFINES
	
	
	// GAIN TYPES
	
	/**
	 * Represents a control for the overall gain on a line.
	 * <p>
	 * Gain is a quantity in decibels (dB) that is added to the intrinsic
	 * decibel level of the audio signal--that is, the level of
	 * the signal before it is altered by the gain control.  A positive
	 * gain amplifies (boosts) the signal's volume, and a negative gain
	 * attenuates (cuts) it.
	 * The gain setting defaults to a value of 0.0 dB, meaning the signal's
	 * loudness is unaffected.   Note that gain measures dB, not amplitude.
	 * The relationship between a gain in decibels and the corresponding
	 * linear amplitude multiplier is:
	 *
	 *<CENTER><CODE> linearScalar = pow(10.0, gainDB/20.0) </CODE></CENTER>
	 * <p>
	 * The <code>FloatControl</code> class has methods to impose a maximum and
	 * minimum allowable value for gain.  However, because an audio signal might
	 * already be at a high amplitude, the maximum setting does not guarantee
	 * that the signal will be undistorted when the gain is applied to it (unless
	 * the maximum is zero or negative). To avoid numeric overflow from excessively
	 * large gain settings, a gain control can implement
	 * clipping, meaning that the signal's amplitude will be limited to the maximum
	 * value representable by its audio format, instead of wrapping around.
	 * <p>
	 * These comments apply to gain controls in general, not just master gain controls.
	 * A line can have more than one gain control.  For example, a mixer (which is
	 * itself a line) might have a master gain control, an auxiliary return control,
	 * a reverb return control, and, on each of its source lines, an individual aux
	 * send and reverb send.
	 *
	 * @see #AUX_SEND
	 * @see #AUX_RETURN
	 * @see #REVERB_SEND
	 * @see #REVERB_RETURN
	 * @see #VOLUME
	 */
	public static final Type MASTER_GAIN		= new Type("Master Gain");
	
	/**
	 * Represents a control for the auxiliary send gain on a line.
	 *
	 * @see #MASTER_GAIN
	 * @see #AUX_RETURN
	 */
	public static final Type AUX_SEND			= new Type("AUX Send");
	
	/**
	 * Represents a control for the auxiliary return gain on a line.
	 *
	 * @see #MASTER_GAIN
	 * @see #AUX_SEND
	 */
	public static final Type AUX_RETURN			= new Type("AUX Return");
	
	/**
	 * Represents a control for the pre-reverb gain on a line.
	 * This control may be used to affect how much
	 * of a line's signal is directed to a mixer's internal reverberation unit.
	 *
	 * @see #MASTER_GAIN
	 * @see #REVERB_RETURN
	 * @see EnumControl.Type#REVERB
	 */
	public static final Type REVERB_SEND		= new Type("Reverb Send");
	
	/**
	 * Represents a control for the post-reverb gain on a line.
	 * This control may be used to control the relative amplitude
	 * of the signal returned from an internal reverberation unit.
	 *
	 * @see #MASTER_GAIN
	 * @see #REVERB_SEND
	 */
	public static final Type REVERB_RETURN		= new Type("Reverb Return");
	
	
	// VOLUME
	
	/**
	 * Represents a control for the volume on a line.
	 */
	/*
	 * $$kk: 08.30.99: ISSUE: what units?  linear or dB?
	 */
	public static final Type VOLUME				= new Type("Volume");
	
	
	// PAN
	
	/**
	 * Represents a control for the relative pan (left-right positioning)
	 * of the signal.  The signal may be mono; the pan setting affects how
	 * it is distributed by the mixer in a stereo mix.  The valid range of values is -1.0
	 * (left channel only) to 1.0 (right channel
	 * only).  The default is 0.0 (centered).
	 *
	 * @see #BALANCE
	 */
	public static final Type PAN				= new Type("Pan");
	
	
	// BALANCE
	
	/**
	 * Represents a control for the relative balance of a stereo signal
	 * between two stereo speakers.  The valid range of values is -1.0 (left channel only) to 1.0 (right channel
	 * only).  The default is 0.0 (centered).
	 *
	 * @see #PAN
	 */
	public static final Type BALANCE			= new Type("Balance");
	
	
	// SAMPLE RATE
	
	/**
	 * Represents a control that changes the sample rate of audio playback.  The net effect
	 * of changing the sample rate depends on the relationship between
	 * the media's natural rate and the rate that is set via this control.
	 * The natural rate is the sample rate that is specified in the data line's
	 * <code>AudioFormat</code> object.  For example, if the natural rate
	 * of the media is 11025 samples per second and the sample rate is set
	 * to 22050 samples per second, the media will play back at twice the
	 * normal speed.
	 * <p>
	 * Changing the sample rate with this control does not affect the data line's
	 * audio format.  Also note that whenever you change a sound's sample rate, a
	 * change in the sound's pitch results.  For example, doubling the sample
	 * rate has the effect of doubling the frequencies in the sound's spectrum,
	 * which raises the pitch by an octave.
	 */
	public static final Type SAMPLE_RATE		= new Type("Sample Rate");
	
	
	// CONSTRUCTOR
	
	/**
	 * Constructs a new float control type.
	 * @param name	the name of the new float control type
	 */
	protected Type(String name) {
	    super(name);
	}
	
    } // class Type
    
} // class FloatControl
